''Clarkia biloba'' is a species of flowering plant in the evening primrose family known by the common name twolobe clarkia and two lobed clarkia.CalFlora Database: ''Clarkia biloba'' (two lobed clarkia)
. accessed 3.23.2013 ''Clarkia biloba'' is

endemic Endemism is the state of a species being found in a single defined geographic location, such as an island, state, nation, country or other defined zone; organisms that are indigenous to a place are not endemic to it if they are also found else ...

California California is a state in the Western United States, located along the Pacific Coast. With nearly 39.2million residents across a total area of approximately , it is the most populous U.S. state and the 3rd largest by area. It is also the m ...

, where it is known from the

Sierra Nevada foothills :''See Sierra Nevada for general information about the mountain range in the United States.'' The ecology of the Sierra Nevada, located in the U.S. states of California and Nevada, is diverse and complex: the plants and animals are a significan ...

; one subspecies can also be found in the

San Francisco Bay Area The San Francisco Bay Area, often referred to as simply the Bay Area, is a populous region surrounding the San Francisco, San Pablo, and Suisun Bay estuaries in Northern California. The Bay Area is defined by the Association of Bay Area Go ...

. It grows in chaparral,

oak woodland An oak woodland is a plant community with a tree canopy dominated by oaks (''Quercus spp.''). In terms of canopy closure, oak woodlands are intermediate between oak savanna, which is more open, and oak forest, which is more closed. Although the ...

s, and yellow pine forest

habitat In ecology, the term habitat summarises the array of resources, physical and biotic factors that are present in an area, such as to support the survival and reproduction of a particular species. A species habitat can be seen as the physical ...

s. As the putative progenitor species of '' Clarkia lingulata'' it is often used in examples of evolution outside the usual model of

allopatric speciation Allopatric speciation () – also referred to as geographic speciation, vicariant speciation, or its earlier name the dumbbell model – is a mode of speciation that occurs when biological populations become geographically isolated from ...

. As such this plant is one of the best plant examples when considering "quantum speciation," a concept closely aligned with

peripatric speciation Peripatric speciation is a mode of speciation in which a new species is formed from an isolated peripheral population. Since peripatric speciation resembles allopatric speciation, in that populations are isolated and prevented from exchanging g ...

parapatric speciation In parapatric speciation, two subpopulations of a species evolve reproductive isolation from one another while continuing to exchange genes. This mode of speciation has three distinguishing characteristics: 1) mating occurs non-randomly, 2) gene ...

and sympatric speciation.

Description

''Clarkia biloba'' is an annual herb producing an erect stem approaching in maximum height. The leaves are linear to lance-shaped and up to 6 centimeters long. Each is borne on a short petiole. The top of the erect stem is occupied by the

inflorescence An inflorescence is a group or cluster of flowers arranged on a Plant stem, stem that is composed of a main branch or a complicated arrangement of branches. Morphology (biology), Morphologically, it is the modified part of the shoot of sperma ...

, which bears hanging buds above open flowers. The pink or red-purple

sepal A sepal () is a part of the flower of angiosperms (flowering plants). Usually green, sepals typically function as protection for the flower in bud, and often as support for the petals when in bloom., p. 106 The term ''sepalum'' was coine ...

s remain fused as the petals spread and emerge from one side of the bud. The petals are up to 2.5 centimeters long and pink to lavender to magenta, sometimes flecked with red. Each petal has a two-lobed tip. There are 8 stamens, some with large lavender anthers and some with smaller, paler anthers. The stigma protrudes past the stamens.

Subspecies

There are three subspecies of this wildflower. * ''Clarkia biloba'' ssp. ''australis'' — Mariposa clarkia; the rarest, known only in the

Merced River The Merced River (), in the central part of the U.S. state of California, is a -long tributary of the San Joaquin River flowing from the Sierra Nevada into the San Joaquin Valley. It is most well known for its swift and steep course through th ...

drainage in the Sierra foothills; threatened by road maintenance and

introduced species An introduced species, alien species, exotic species, adventive species, immigrant species, foreign species, non-indigenous species, or non-native species is a species living outside its native distributional range, but which has arrived ther ...

. * ''Clarkia biloba'' ssp. ''biloba'' — two lobed clarkia * ''Clarkia biloba'' ssp. ''brandegeeae'' — Brandegee's clarkia CalFlora: ''Clarkia biloba'' ssp. ''brandegeeae''
/ref>

References

External links

Jepson Manual Profile — ''Clarkia biloba''''Clarkia biloba'' Photo gallery
{{Taxonbar, from=Q5127535 biloba Endemic flora of California Flora of the Sierra Nevada (United States) Plants described in 1855 Flora without expected TNC conservation status